An enterprise customer may enable users (e.g., employees of the enterprise customer) to access communication services using a Private Branch Exchange (PBX). For example, the PBX can be used to enable the enterprise customer to subscribe to a limited number of connections to a circuit switched network, e.g., the Public Switched Telephone Network (PSTN). The limited number of connections can then be shared among a large number of employees. Prior to transitioning services from a traditional circuit switched network to the IMS network, many enterprise customers require a similar capability from the IMS network. However, unlike traditional circuit switched networks, Internet Protocol (IP) Multimedia Subsystem (IMS) networks have been initially designed for single user endpoint devices that access the IMS network through a single Proxy-Call Session Control Function (P-CSCF).